Shortness of breath and fatigue

Patient: I experience sudden shortness of breath and fatigue. It has been a month. I am 20 yo female, active doing physical exercise. This really effect my exercise routine especially when i run, i have to stop many times to take long deep breath. I visited a GP, she did physical examination on me and said everything is fine. She was afraid that i have GERD cuz i experienced dyspepsia before, she gave me drugs for that, ive been taking it for a week but nothing change.

Symptoms: Shortness of breath, fatigue

Doctor: